A stepping motor has characteristics as follows.
Because it is able to control the angle of rotation using the number of supplied pulse signals, no feedback is necessary, which enables precise control to be achieved with a simple configuration.
The speed of rotation can be changed by changing the frequency of a pulse signal.
Once the initial position of a movable body to be driven is determined, the movable body can be moved to a target position without the need to detect the position of the movable body. For example, it is suitable to drive a carriage and a mirror in an image forming apparatus.
Because it has an excellent response when activated, stopped, or rotated inversely, it is suitable to drive, for example, a resist roller in an image forming apparatus.
As a driving method of the stepping-motor, there are 2-phase excitation, 1-2-phase excitation, W1-2-phase excitation, 2W1-2-phase excitation, and so forth. In 2-phase excitation and 1-2-phase excitation, an excitation phase pattern comprising four steps is repeated for one rotation. In W1-2-phase excitation, because it includes current control, an excitation phase pattern comprising 16 steps is repeated for one rotation. In 2W1-2-phase excitation, because it also includes current control, an excitation phase pattern comprising 32 steps is repeated for one rotation.
When the stepping motor as above is driven, it is necessary to manage which phase among the respective phases is being excited.
In the case of 2-phase excitation and 1-2-phase excitation, the management is easy because the excitation phase pattern is simple.
In the case of W1-2-phase excitation, however, the management becomes complicated because its excitation phase pattern including current control is complicated. In the case of 2W1-2 phase excitation, the management is complicated, too, because its excitation phase pattern including current control is complicated.